This invention relates generally to the monitoring of jaw movements on a gripper mechanism of a collator machine or the like, to detect the gripping of more than one or no sheet of paper during any single operational cycle.
Single sheet thickness detectors to monitor jaw movement in collating machines, are well known, such as those disclosed in U.S. Pat. Nos. 3,744,287 and 3,885,780. Such detectors include a mechanical linkage connection to the pivot shaft of a movable jaw carried by the gripper lever arm by means of which an electrical contactor is displaced relative to adjustably spaced contacts also carried on the gripper arm. The contacts are electrically connected to a malfunction indicator and/or a stop mechanism for interrupting operation of the associated collating machine in the event more than one or no sheet of paper is gripped between the jaws during an operational cycle of the gripper mechanism. Operation of the gripper mechanism is thereby limited to withdrawing a single sheet of paper at a time from a storage magazine for deposit onto a moving conveyor. The foregoing type of sheet thickness detection arrangement, mounted entirely on the oscillating gripper arm, requires modification of the movable jaw or its pivot mounting and is inherently difficult to assemble, adjust and maintain. Detection reliability is thereby adversely affected.
It is therefore an important object of the present invention to provide a thickness detection arrangement for mounting on an oscillating gripper arm that is simple to assemble and adjust. A further object is to provide for more sensitive and reliable detection of jaw movement on the gripper arm of a gripper mechanism in a collating machine.